That's the thing, unless we're dealing with something absolutely abhorrent "hostage situations etc", police can't be sent in unless there's solid reason to believe a crime was committed in the first place. Sometimes it feels like our rules on the matter really work against us, but it's all about making sure we don't have police sent out over rumors and baseless ill-speak.
Edit: Unannounced raids are only permitted if it's believed that any evidence of crime can be eliminated or a crime actually can be committed in the time police take to announce themselves. That's a "No-Knock" Warrant.
Also, our County Sheriff and Police offices aren't exactly famous for seamless cooperation. A good example is the city below me having a smaller legal province "Chapmantown", within itself, which caused Chapmantown to become a hive of crime, as on top of insufficient police forces in the area, there was no rights given to the Chico police to intervene to handle misdoings.
Edit: I quoted myself and double posted. Fucking end me my dudes.